Determining a geospatial location of a transmitter (e.g., a cell phone) may have application in civilian search and rescue, law enforcement, and military environments. Phase measurements of signals emitted by the transmitter and received by two or more antennas may be used to determine estimated locations of the transmitter. For example, the antennas at fixed locations may receive the signals and an estimate of the location of the transmitter may be determined based on phase measurements of the signals. The phase measurements of the signals received at fixed spatial points may not enable estimation of the location of the transmitter with a high degree of accuracy.